I know a map doesn't tell the whole story but I want to understand more about what part of the story they do tell. Here are two turbos that are somewhat comparable on the butt dyno - the 2560 and Mazdaspeed IHI with the 15g wheel upgrade.

The pressure numbers listed up the side are atmospheres (BAR), correct? On these charts, 1 Bar is what we inhale and 2 Bars is ~14.7psi on the boost gauge, correct? Bigger turbos flow more (x-axis) and allow higher pressure (y-axis) at the possible expense of spool/lag time, correct?

How would you expect these two turbos to perform in the real world (all other things equal) and do you think flow is more important than pressure or vice versa? Is a good balance the better way to look at it?

It's cold and wet here and since I can't drive the car and haven't found the motivation to dig into the winter projects, I thought a little book work might be helpful. Informed opinions much appreciated - thanks!

 

two links for you:

Stealth 316 - Turbocharger Compressor Flow Maps

Compressor Maps | Turbobygarrett

 

I read through them once and understood what I was reading (I think). Now, I need to go through about 5 more times and pencil out some actual calculations to see if I can put this in the mythical 'applied knowledge' category.

I haven't searched yet but does anyone know the basic VE for our engines (BP4W head)? I appreciate there are dozens of variables so perhaps just a ballpark range? Very interesting - thanks for the links Brain!

 

Compressor maps won't show any spool or lag characteristics, that's what turbine maps are for (well sort of).

Compressor maps will show you exactly what it says, how much air the turbo can flow at any given pressure ratio (the y-axis, not BAR) and how efficiently it does it and at what wheel speed. You can use this information and some specifics of your engine to guesstimate if you will have problems with surge and if the compressor can meet your goals.

Oh and the answer to your question is EFR6258. It's compressor map makes these look like a joke, oh and it will spool much faster.

 

Good read. Props!

6258 map:


Taken from this page of all EFR maps:
http://www.turbos.com/efr-compressor...and-specs.html

 

Heres a pretty nifty spreadsheet to help you understand how a certain compressor will work with your engine. Right now its setup for a 2.5 liter subaru so you'll need to change the displacement and the VE numbers. The 15t compressor is in the spreadsheet.

 

True - that is on the list for... someday. I could have rephrased the question to be 'what's the best without spending a penny of additional budget?'

Leafy, I didn't see the spreadsheet attached. Do you have a link?

 

I gues it cant do xls and I didnt notice it failing. I dont have time now maybe tomorrow.

 

Here is my spreadsheet for the 1.8L.
https://docs.google.com/spreadsheet/...ya3p6MGc#gid=0

 

Finally got around to posting the one I use. Credit goes to a whole litany of people on rom raider forums. I've only just made the most recent update, and that was really just combining tow sheets.

https://dl.dropbox.com/u/18163809/co...ap_combine.xls

 

Your VE is much higher than mine. Is this a more accurate representation? If so I will update mine as well.

 

/thread

 

Ugh...I haven't been here in months, yet I still remember the garbage that Tech spewed...

 

No, thats all subaru numbers in there.